Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$182.34	11.228%	$202.8131	$202.81	$202.80	$202.80
Purchase #2	$164.89	13.330%	$186.8698	$186.87	$186.85	$186.90
Purchase #3	$199.76	11.650%	$223.032	$223.03	$223.05	$223.00
Purchase #4	$26.40	7.650%	$28.4196	$28.42	$28.40	$28.40
Purchase #5	$138.52	13.479%	$157.1911	$157.19	$157.20	$157.20
Purchase #6	$52.83	12.600%	$59.4866	$59.49	$59.50	$59.50
Purchase #7	$175.57	12.119%	$196.8473	$196.85	$196.85	$196.80
7 purchase totals =	$940.31		$1,054.6595	$1,054.66	$1,054.65	$1,054.60